The basis for the development described hereinafter is, in particular, the desire for greater logistical transparency in logistics networks and the supply chains they contain.
An essential element of every logistical supply chain is the process of changing the location of logistic goods, which is referred to as transport. In order to change locations, a distance must always be traversed. Hence, the physical size of the route is always a variable in a given transport operation. The process of changing locations takes a specific period of time that depends on the route. Thus, time, in addition to the route, is another variable in the process of transporting goods. These two variables determine the speed, which must be considered a vital characteristic for the efficiency of a supply chain in logistics.
In maritime freight logistics, goods are usually housed in containers whose outer dimensions are standardized. Such containers usually are not in the possession of the customer, supplier or logistics service provider. Instead, the containers are in the possession of the maritime shipping companies. Such containers usually must be returned once a transport request has been carried out. In this environment, more than 20 million containers are currently being moved for transport times of as much as 80 days, including incoming and outgoing inland transport. During the period of transport the containers are virtually invisible to the sender, the receiver and the logistics handlers, as well as to the owner. This means that neither the present whereabouts nor the time can be reliably ascertained, which not only gives rise to the usual problems such as ullage, loss and theft of both the goods in the containers and the containers themselves, but also, most notably, creates major disadvantages with regard to inventory management. These disadvantages involve, for example, search times for individual containers, allocation problems, demand coverage problems and lack of storage space, non-optimized warehousing costs, and a generally very high communication expenditure and associated costs in order to obtain information on the present whereabouts of the containers.
As a result, intensive efforts have been made in the past to find solutions that would eliminate these non-transparences at acceptable marginal costs. No universal solutions have been created so far, however. The solutions currently on the market are either significantly too expensive, not technologically mature, too operationally complex to install or too demanding or venturesome in terms of communication requirements, thus affecting the amount of the communication costs incurred. All present-day container tracking technologies are geared to the monitoring of freight, instead of focusing on monitoring the containers inclusive of the freight they contain. Thus far there is no simple, inexpensive, readily scalable and easy to-install variant that could be used worldwide both from a hardware standpoint and from that of communication costs.
With the establishment of cellular communication networks, new possibilities have arisen for locating communication terminals designed for communication in cellular communication networks using the resources available in those networks.
An overview of the current general state of the art is most easily approached from two angles. On the one hand, there is the hardware engineering aspect, having to do with the technical solutions embodied by the terminals that are currently on the market. On the other hand, it is also necessary to consider the locating technologies that are already available.
In the field of T&T (Tracking & Tracing) applications for container logistics, RFID systems must be ruled out precisely because of their very high global infrastructure deployment. Satellite positioning methods are used, but due to communication costs and line of sight problems, they are confined to individual routes for freight monitoring, and are not generally used to monitor the containers themselves due to their cost, their influence on position, and the energy they require. GPS/GMS or GPS/GPRS systems have seen the most widespread practical use so far: to determine a location, the installed GPS chip queries the current position and then, for example, transmits it to a server over a GSM channel as a text message or via GPRS as a TCP/IP [Transport Control Protocol/Internet Protocol] message. The cost of operation varies with the country in which the system is being used and the communication channel. If GPS cannot be used for location determination or it is necessary to save the cost of antennas and chips, the radio cell of a cellular communication network can also, alternatively, be used for locating purposes. These mobile radio network dependent locating methods use the information from the location directory and the visitor location register to identify the radio cell in which the user or the communication terminal assigned to the user is located. This technique is generally known as Cell Identification (Cell ID) or Cell of Origin (COO) positioning. This type of location determination, however, is relatively inaccurate and dependent on radio cell size. An improvement in locating accuracy can be obtained by additional field strength measurement or Received Signal Strength (RSS) indication. The location accuracies that can be achieved in this way are between approximately 200 m and 10 km, depending on the size of the radio cells.
An extension of the aforesaid locating solution provides that to determine a location, the propagation delay between the signals from at least three neighboring base stations is detected in the communication terminal and transmitted to the base station. There are already several types of methods operating on this basis that can be used for this purpose. These include, for example, Time of arrival (ToA) methods, Time Difference of Arrival (DoA) methods and Angle of Arrival (AoA) methods. To improve position accuracy, the so-called Enhanced Observed Time Difference (E-OTD) method is used in GSM networks in combination with General Packet Radio Service (GPRS). In UMTS [Universal Mobile Telecommunication Systems], the analogous method is known as the Observed Time Difference of Arrival (OTDOA) method. It furnishes an improvement in position accuracy of 30 m to 50 m, which also has to do with the fact that a UMTS has smaller radio cells. A key element here is that the mobile communication terminal performs this calculation locally and then transmits via GSM, GPRSU/UMTS or the like. Here again, communication costs are generated through the use of a communication channel.
The general prior art also already includes indirect locating methods based on an approach similar to that of the aforesaid methods. In those methods, the measurement of at least three cell IDs is detected by the mobile communication terminal and transmitted to the provider of the cellular communication network, which, in turn, then calculates the location and transmits the results back to the communication terminal. This scheme thus actually makes use of two communication channels, since the communication terminal receives the information about its own location by that route.
WO 99/34611 A2 describes a method for tracking a mobile communication terminal in a cellular communication network. Here, the communication terminal dials into and back out of a radio cell. The radio cell in which the communication terminal was located can thus be identified. Since radio cells vary in size and can have large coverage areas of several kilometers, the known method furnishes only a very rough approximation of the location of the mobile communication terminal.
DE 10 2005 041 453 A1 discloses a method for locating a mobile terminal in a multicell radio arrangement. In this method, the central equipment initiates the location process by placing connected radio base stations in a measuring state, enabling the radio base stations to send test data to the mobile terminal that is to be located. The mobile terminal is prompted by the transmitted test data to send a response message to the radio base station, thus permitting a registration of the resultant received field strengths at the positions of the radio base stations. The measured received field strengths for the mobile terminal are then retrieved from the radio base stations by the central device, and this information can then be used to calculate location information by a triangulation method. A disadvantage of this known method is the energy consumption at the communication terminal, since energy is needed for and consumed by the existing connection.
DE 103 07 592 A1 describes a method for localizing a mobile communication terminal. For this purpose, the communication terminal sends a request message for a communication channel to a neighboring base station, which sends the mobile terminal an acknowledgement containing a time delay that is occurring, known as a TA value. This process is carried out with at least two more neighboring base stations, and the TA values obtained can thus be used to determine the position of the mobile terminal by a triangulation calculation. In this known solution, as well, test messages are transmitted between the communication terminal and a central station of the communication network, thus resulting in costs, or at the very least an increase in energy consumption.
There have been no central locating methods heretofore that permit the global positioning of an object with an accuracy of less than 200 meters without chargeable data or information transmission and with minimal power demand.
Turning now to the hardware aspect, here again, there are already a great many real-time locating systems available. Essentially, locating systems based on WLAN, RFID, NFC and the like do exist, but can be used in the container logistics sector only in certain cases, and then only in a very limited, local context. Nevertheless, a number of locating systems are already being used in the container logistics industry. These can basically be divided into satellite-supported systems and GSM/GPRS-supported systems. Whereas satellite-supported systems are used primarily on the individual shipment level, including the monitoring of temperature, humidity, shock or the like, GPS/GSM systems have come into much more widespread use. Due to their high hardware costs, however, combined with not inconsiderable communication costs, most of these known solutions have remained niche solutions that have not succeeded in gaining global acceptance.
In summary, then, there is currently no way of tracking relatively large numbers of containers in real time for long periods at low cost. One reason for this is that there are no communication and locating methods that are capable of advantageously global communication and location determination. Furthermore, there is currently no hardware on the market that would be able to perform this function at manageable cost. Due to the present situation, it is impossible for a logistics handler, shipowner or logistics customer to gain transparency in transport in a cost-effective manner.
Proceeding from the aforesaid state of the art, the object on which the invention is based is to provide solutions for locating mobile communication terminals in cellular communication networks by means of which the aforesaid disadvantages can be avoided. In particular, solutions are to be provided that offer a simple, cost-effective, readily scalable and easy to install locating capability, and with which locating can take place without chargeable data or information transmission and with minimal power demand.